This invention relates to refrigeration, and more particularly to improvements in both apparatus and operating aspects of refrigeration systems of the vapor-compression type utilizing capillary tube restrictors as the throttling means.
Capillary tube restrictors are widely used in refrigeration systems to meter the flow of liquid refrigerant between the condenser and the evaporator. The flow characteristics of an overall system are basically a function of the capillary tube dimensions, i.e., length and inside diameter, in combination with dimensions and performance of other refrigerant circuit components of the system. Optimum balance between mass-flow rate of refrigerant capable of being handled by the capillary tube restrictor and system refrigerant flow-rate may be resolved to a line function of operating conditions. Deviations from a preferred line function can be tolerated, for example in the field of household refrigeration appliances using relatively low capacity, fractional horsepower compressors.
Heretofore, in larger capacity units, where high efficiency and wide variations in operating conditions must be dealt with capillary tube restrictors have met with limited success. Instead, resort has been had to the more costly thermostatically controlled expansion valve as a metering device. Control of such a valve is a function of evaporator loading as determined by the evaporator superheat temperature by a sensing element operably coupled with means effective to modulate the rate of flow through the valve.
It is an objective of my invention to provide a refrigeration system with improved capillary tube restrictor means overcoming the above briefly described shortcomings of such restrictors and achieving the operating flexibility afforded by more costly thermostatically controlled expansion valves.
It is a further and more general objective of the invention to provide refrigeration apparatus with improved capillary tube restrictor means affording efficient operation over a variety of operating conditions.
It is a further objective of the invention to provide means for improving operation of a refrigeration system of otherwise conventional design.
It is also a objective of the invention to provide a novel and improved method of operation of a refrigeration system utilizing a capillary tube restrictor as the metering device.